1. Field of the Invention
The present invention relates in general to an automatic transmission shift control device with a park lock, and more particularly to a manually operable park lock releasing mechanism for such a shift control device.
2. Description of the Prior Art
An example of a prior art park lock releasing mechanism for an automatic transmission shift control device is disclosed in "Service Report No. 622 (R32-1) C-37. published by Nissan Motor Co., Ltd. and also shown in FIG. 7 hereof.
Referring to FIG. 12, a selector lever 10 is pivotally installed on a vehicle body (not shown). A position pin 12 is installed on the selector lever 10 for up-and-down movement relative thereto and engageable with detents of a position plate 14 for holding the selector lever 10 in gear positions such as a "P (parking)" position, "R (reverse)" position, "N (neutral)" position, "D (drive)" position, "2 (second)" position, and "1 (first)" position, respectively. A gear position indicator and top panel assembly 16 is disposed for concealment of the position pin 12, the position plate 14, etc. and for indication of a selected gear position. The gear position indicator and top panel assembly 16 is formed with a slot 18 such that the selector lever 10 is movable in the slot 18 in the forward and rearward directions of the vehicle body. A bushing 20 is rotatably installed on the selector lever 10 to prevent disengagement of the position pin 12 from the "P" position defining detent of the position plate 14, i.e., to prevent shifting of the selector lever 10 out of the "P" position, once the selector lever 10 is shifted to the "P" position and unless the foot brake is applied. A release button 22 is installed on the selector lever 10 on the rear side thereof and urged upward by a spring (not shown). A release lever 24 is disposed inside of the gear position indicator and top panel assembly 16 and pivotally installed on the selector lever 10 by means of a pivot 24a such that pushing of the release button 22 can cause the bushing 20 to rotate into a position where an opening 26 of the bushing 20 is aligned with the position pin 12 for making the position pin 12 disengageable from the "P" position defining detent of the position plate 14. A cover member 28 is provided for closing the slot 18 and formed with a notch 30 for allowing movement of the release button 22 therethrough.
A similar park lock mechanism utilizing a position pin, bushing, etc. is disclosed in U.S. Pat. No. 4,909,096, issued on Mar. 20, 1990, in the name of Satoshi Kobayashi and assigned to one of the assignees of this application.
A disadvantage of the above described prior art mechanism is that since the release button 22 is installed on the selector lever 10 to move together therewith the slot 18 of the gear position indicator and top panel assembly 16 is required to have an additional length corresponding to the size of the release button 22, causing some design restrictions.
Another disadvantage is that small trashes or the like substances and liquid such as juice may possibly intrude into the inside of the gear position indicator and top panel assembly 16 through the notch 30.